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Bulle & Eureka Parts & Restorations

The place to come for all your Bulle and Eureka restoration parts.

Code

BU014

These Isochron springs are made to the original design but are  made from 0.15mm C902 steel instead of Invar. 18 coils of 4mm, 2 half end coils at right angles . They are  the only springs that are consistent with the compositional characteristics of the origianl Bulle spring as shown in the laboratory test conducted over 2004 / 2005. The original patent specifies Invar, but this is much too soft for use as a spring. Please see The Isochron Story.  Each is supplied in a clear perspex box.

C902 is a nickel-iron-chromium alloy made precipitation hardenable by additions of aluminum and titanium. The titanium content also helps provide a controllable thermoelastic coefficient, which is the alloy's outstanding characteristic. The alloy can be processed to have a constant modulus of elasticity at temperatures from -50°F to 150°F (-45 to 65°C).

Price

£10.00

Bulle C902 Isochron Spring

Full Technical Specification

(Ni SPAN C 902, Nispan C, UNS N09902; BS 3127; SAE AMS 5210, 5221, 5223, 5225)